To be brutally honest, there's not much in your army that fits well together, and you're not taking advantage of the strengths of chaos. Also, I had some trouble with your format. Its a pain on the eyes.

Terminator armor on HQs: Since retinues are no longer an option, having hq's in termi armor doesn't have nearly the benefit as seen in 3rd edition. For one thing, the lord no longer has the retinue's protection when deep striking, and second, if you're footslogging him across the board, then he's incredibly slow and unlikely to reach combat before turn 4. It's far better to give the lord a movement modifier, such as flight, or simply place him in a rhino with a troop squad.

Terminators: What's the reason for upgrading this unit to a.c's? They already have an inordinate number of attacks, what, between the claws and the IoK. These points might be better spent elsewhere, as they already have 5 attacks each on the charge. This is more than sufficient and will statistically result in the death of 9+ marines on the charge. That's plenty to take down most enemy units.

Landraider: Drop the havoc launcher. It has no synergy with the vehicle, and land radiers are already expensive. Keep their points down to a minimum (daemonic possession is a necessary upgrade, so it's not extraneous).

Chaos defiler: Swap all the secondary weapons to additional c.c. attacks. The defiler should only be firing it's battle cannon anyways, so the secondary weapons nearly always lay dormant. By having maxing out your c.c. abilities, the defiler can effectively deal with enemy units in c.c.

Possessed: The squad is too small and will easily get gunned down at range at the 2500 point level. Also, there's no reason to have an a.c. in this squad, as you're not taking advantage of power weapons. Finally, how do you plan on getting them into c.c.? While you might rely on a good role from the random possessed options, having a movement modifier is far from certain. For this reason, the possessed need a rhino. You should consider increasing the squad count to 8.

That said, possessed simply are not worth their points in 4th edition (they weren't worth it in 3rd either). Drop the unit and use the points for either further upgrades or additional units.

Berzerkers: Fine

Spawn: Drop them and spend the points elsewhere. They, like possessed, just are not worth their cost.

10x marine sqaud: Drop the combi-bolter and take a power fist over the basic power weapon. The unit has a solid 10 wounds protecting it's a.c., so the squad needs to be maximizing it's c.c. output each round.

On a side note: Chaos marines are generally designed for special weapons, but not heavy weapons. This was true in 3rd edition and even more so in 4th. This unit would be far better with swapping the autocannon for another melta and then giving the squad a rhino. Mobility is everything. Against superior ranged armies (i.e, Tau, I.G.) or against highly mobile armies (mech Tau, mech eldar, mech I.G., mech D.E., basically anything mech), you'll need the rhinos for getting your marines into position. Against superior ranged armies in particular, your marines will be required to advance upon the enemy ranks, and not having a rhino makes this extremely problematic.

Also, special weapons are conducive for allowing the marines their natural movement, whereas heavy weapons are not. In my experience, marines tend to move around, even when put in a stationary position.

5x marine squad: This unit isn't really doing anything. It doesn't have enough wounds to support the a.c., and it isn't producing enough ranged or c.c. power to pose a threat. Additionally, it's very slow.

I hope these comments aren't too critical. They were aimed at getting your army to utilize the best options for the point values. If you want, post a revised list, and I'll go over it again.